Apparatus for measuring the softening point of a solid

ABSTRACT

THIS INVENTION RELATES TO APPARATUS FOR DETERMINING THE SOFTENING POINT OF A SOLID, SUCH AS ELECTRODE BINDER PITCH OR THE LIKE. THIS APPARATUS FOR DETERMINING THE SOFTENING POINT OF A SOLID SAMPLE HAS A FIRST HEATING MEANS AND A SECOND HEATING MEANS, EACH FOR CONTAINING A SOLID SAMPLE AND FOR HEATING THE SOLID SAMPLE TO ITS SOFTENING POINT TO A PREDETERMINED UNIFORM RATE OF TEMPERATURE RISE AND HAVING SENSING MEANS FOR CONTINUOUSLY MEASURING THE TEMPERATURE WITHIN THE FIRST HEATING MEANS AND THE SECOND HEATING MEANS DURING THE HEATING OF THE SOLID SAMPLE. SWITCH GEAR MEANS AND CONNECTED TO   THE FIRST HEATING MEANS AND THE SECOND HEATING MEANS TO ALTERNATELY CONNECT THE FIRST HEATING MEANS AND THEN THE SECOND HEATING MEANS TO THE APPARATUS. TEMPERATURE CONTROL MEANS ARE CONNECTED TO THE SWITCH GEAR MEANS FOR CONTROLLING THE UNIFORM RATE OF TEMPERATURE RISE IN THE FIRST HEATING MEANS AND IN THE SECOND HEATING MEANS, AND TEMPERATURE RECORDING MEANS ARE CONNECTED TO THE TEMPERATURE CONTROL MEANS AND THE SWITCH GEAR MEANS FOR RECORDING THE TEMPERATURE RISE IN THE SOLID SAMPLE AND THE SOFTENING POINT OF THE SOLID SAMPLE.

United States Patent G0ln1/00 73/15,17

[72] Inventors Glenn E. Bowers McKeesportt Pa. Richard E. Edwards, Jr., Bethel Park Borough, PI. [21 Appl. No. 752,932 [22] Filed Aug. 15, 1968 [45] Patented June 28, 1971 Assignor to United States Steel Corporation.

[54] APPARATUS FOR MEASURING THE SOFTENING POINT OF A SOLID 8 Claims, 13 Drawing Figs.

[52] US. Cl [51] 1nt.Cl.... [50] Field of Search [56] References Cited UNITED STATES PATENTS 3,187,556 6/1965 Ehlers t.

3,276,692 10/ 1 966 Schultz...

. PrimaryExaminer-Richard C. Queisser Assistant Examiner-John K. Lunsford Attorney-Robert .l. Leek, Jr.

ABSTRACT: This invention relates to apparatusfor determining the softening point of a solid, such as electrode binder pitch or the like. This apparatus for determining the softening point of a solid sample has a first heating means and a second heating means, each for containing a solid sample and for heating the solid sample to its softening point at a predetermined uniform rate of temperature rise and having sensing means for continuously measuring the temperature within the first heating means and the second heating means during the heating of the solid sample. Switch gear means are connected to the first heating means and the second heating means to alternately connect the first heating means and then the second heating means to the apparatus. Temperature control means are connected to the switch gear means for controlling the uniform rate of temperature rise in the first heating means and in the second heating means, and temperature recording means are connected to the temperature control means and the switch gear means for recording the temperature rise in the solid sample and the softening point of the solid sample.

III 3 APPARATUS FOR MEASURING THE SOFTENING POINT OF A SOLID BACKGROUND OF THE INVENTION Coal tar pitch, a residue from the distillation of coal tar, is utilized as a binder for many carbon products, and more particularly as a binder for carbon anode electrodes employed in the electrical reduction of alumina to the pure metal. Such electrode binder pitch is produced to exact specifications in order that the finished anode electrodes or carbon products will have the required specified characteristics of density, electrical resistance, softening temperature and the like.

The softening point ofa coal tar pitch is the most common criterion of binder pitch quality, if determined according to ASTM D23l9-64T, the standard method of test for the softening point of pitchby the cube-in-air method, and ifit is performed by conventionalapparatus Model 8H502 manufactured by the American Instrument Company, Silver Springs, Md.

The conventional apparatus has an oven having an outer shell and an inner,shell provided with registering mica windows for viewing the interior of the inner shell. The outer shell is fitted with a cover having a centrally located hole for a cork into which a thermometer is inserted to measure the inner shell temperature. The inner shell has an inner support ring on which test specimen'hooks are mounted. An inner pan in the inner shell is provided with three short brass legs which rest on the bottom of the inner shell so that the inner pan is raised a predetermined distancefrom the floor of the inner shell of the oven. In order to heat'the oven, an electrical heating element is disposed below the inner pan and is controlled by a variable voltage source, such as a variable transformer for the purpose of regulating the temperature in the oven. The test samples of coal tar pitch are heated in a container and poured into a lightly greased mold having about one-halfinch cubic cavities therein, each mold cavity having a core pin to provide a hole in the pitch sample for mounting such pitch sample on the test specimen hooks. These sample test cubes are mounted by means of the hooks on the support ring and suspended at predetermined locations within the oven with the thermometer mounted between the test sample cubes. With the oven and the specimens at room temperature the operator turns on the heating element and begins to record the rate of temperature increase within the oven, endeavoring to control the temperature rise within the oven between about 4 and 6 C. per minute (up to a temperature of about 50 C. below the softening point) and between about 4.5to 5.5C. per minute for the last 50 C. up to the softening point of the coal tar pitch test sample cubes.

Since coal tar pitch is not a crystalline solid, there is no sharp transition point from the solid form to the liquid form. Such coal tar pitch cubes begin to soften at a temperature about 10 C. below the softening point and then slowly sag and drop from the hanger hooks. The softening point of the coal tar pitch test sample cubes is defined as the thermometer reading at the instant when the softened coal tar pitch cube touches the inner pan at the bottom of the oven. The operator visually observes the pitch cubes and the thermometer and records the temperature at which the softened coal tar pitch test specimen cubes touch the inner pan of the oven. Temperature readings are estimated to the nearest 025C. and the average temperature is recorded for two specimens. If the recorded values do not differ from each other by more than 1.0 C., the test is satisfactory.

This conventional apparatus for determining the softening point of a solid, such as a coal tar pitch specimen, utilizes crude heating control, requires an excessive amount of the operator's time, usually in the neighborhood of about l520 minutes per sample, and permits too much error in the test results, often resulting in innumerable delays and in the scrapping of satisfactory coal tar pitch which the tests erroneously indicate as not conforming to the required specifics trons.

OBJECTS OF THE INVENTION It is the general object of this invention to avoid and overcome the foregoing and other difficulties of and objections to prior art practices by the provision of an improved apparatus for determining the softening point of a solid, such as for example electrode binder pitch or coal tar pitch, which apparatus:

l. maintains the rate of temperature rise in the heating means at 5 C.i0.02 C. per minute automatically, thereby resulting in improved precision and accuracy in the determination of the softening point;

2. permits the testing ofa plurality of specimens, such as six, thereby permitting plural numbers, such as three different specification samples to be measured at one time with attendant reduction of test total time by about one-third;

3. records permanently the softening point of each pitch specimen automatically, thereby freeing the operator from the tedious task of recording during the heating phase of the softening point determination; and

4. results in an accurate determination of the softening point characteristics of electrode binder pitches to prevent errors or deviations from the customer specification and the unnecessary scrapping of suitable electrode binder pitches.

BRIEF SUMMARY OF THE INVENTION The aforesaid objects of this invention and other objects which will become apparent as the description proceeds are achieved by providing an improved apparatus for determining the softening point ofa solid, such as an electrode binder pitch or coal tar pitch. This apparatus for determining the softening point of a solid sample has a first heating means and a second heating means, each for containing a solid sample and for heating the solid sample to its softening point at a predetermined uniform rate of temperature rise and having sensing means for continuously measuring the temperature within the first heating means and the second heating means during the heating of the solid sample. Switch gear means are connected to the first heating means and the second heating means to alternately connect the first heating means and then the second heating means to the apparatus. Temperature control means are connected to the switch gear means for controlling the uniform rate of temperature rise in the first heating means and in the second heating means, and temperature recording means are connected to the temperature control means and the switch gear means for recording the temperature rise in the solid sample and the softening point of the solid sample.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS For a better understanding. of this invention reference should be had to the accompanying drawings, wherein like numerals of reference indicate several parts throughout the several views and wherein:

FIG. 1A is a front view of improved apparatus for testing the softening point of a solid and showing the first heating means, the second heating means, the switch gear means, the temperature control means and the recording means;

FIG. 1B is a rear view of the apparatus shown in FIG. 1A showing the inner connected wiring of the first heating means, the second heating means, the switch gear means, the temperature control means and the temperature recording means;

FIG. 2A is a plan view of one of the first heating means and the second heating means, in this case the first heating means;

FIG. 2B is a front view of the first heating means;

FIG. 2C is a horizontal sectional view of the first heating means taken along the line lIC-IIC of FIG. 2B in the direction of the arrows;

FIG. 2D is a vertical sectional view of the first heating means taken along the line llD-IID of FIG. 2B in the direction of the arrows;

FIG. 3 is an electrical wiring diagram of the first heating means;

FIG. 4 is a side elevational view of one of the mechanical balance switches employed in the first heating means and in the second heating means;

FIG. 5 is a plan view showing the general arrangement of electrical components of the switch gear means;

FIG. 6 is a schematic wiring diagram of the switch gear means;

FIG. 7 is a schematic wiring diagram of the temperature controller means;

FIG. 8 is a schematic wiring diagram of the temperature recorder means;

FIG. 9 is a timing chart illustrating the operation of the apparatus; and

FIG. I0 is a fragmentary front view of the temperature recording pen, event marking pens and the chart of the recorder.

Although the principles of this invention are broadly applicable to apparatus for determining the softening point of a solid, this invention is particularly adapted for use in conjunction with apparatus for determining the softening point of electrode binder pitch or coal tar pitch specimens and hence it has been so illustrated and will be do described.

DETAILED DESCRIPTION With specific reference to the form of this invention illustrated in the drawings and referring particularly to FIGS. 1A and IB, an apparatus for determining the softening point of a solid, such as an electrode binder pitch or coal tar pitch, is indicated generally by the reference numeral 10.

The apparatus 10 has a first heating means 12a (FIGS. 2A- 2D) and a second heating means 12b (FIGS. IA, 18), each for containing a plurality of, for example, six solid samples 14 (FIGS. 2D, 4) and for heating the solid samples I4 to their softening point at a predetermined rate of temperature rise.

HEATING MEANS I2a, 12b

Since the heating means 12a and 12b are similar, it is necessary only to describe the first heating means 12a (FIGS. 2A- 2D). The first heating means 120 is a boxlike structure mounted on ajunction and power distribution box 13a (FIGS. 28; 2D) having an outer shell 16 (FIGS. 2A, 2B, 2C) and an inner shell I8 (FIGS. 2A, 2B, 2C) separated by insulation 20 (FIGS. 28, 2C) at the top I2al (FIG. 2A) ,sides l2a2 FIGS. 2B, 2C, 2D) 12 23 (FIGS. 28, 2C), bottom l2a4 (FIG. 2B) and back I2a5 (FIGS. 2A, 2B, 2C, 2D). A door 22 (FIGS. 2A- 2D) having a shield 14' (FIGS. 2A2D) and double glass panes 22a (FIGS. 2B, 2C) separated by a vacuum is hinged at 22b (FIGS. 2A, 2B, 2C) and is latched at 220 (FIG. 2C) and sealed at (FIGS. 2A, 28) to the top 12aI, sides 12112, I2a3 and bottom l2a4. In order to provide an air circulation space 24 (FIGS. 2B, 2C) within the first oven 120, a sample chamber 26 (FIGS. 2B2D) defined by a U-shaped wall 26a (FIGS. 28, 2C) is spaced from the inner shell 18 along the sidewalls l2a2, 1203 and rear wall l2a5, which wall 26a is provided with circulation holes 280 (FIGS. 2B2D). The back wall 12115 is sealed at 150 (FIGS. 2A, 2D) to the sidewalls 12a2, 1203, top wall 12a] and bottom wall 12114 and is secured thereto by bolts I7 (FIGS. 2C, 2D). The means utilized to circulate air through the circulation space 24 and the sample chamber 26 in the direction of the arrows (FIG. 2C) comprises in addition to the circulation holes 280, a blower 30 (FIGS. 2C, 2D) driven by a motor 32 (FIGS. 2A, 2C, 2D), which motor 32 in turn is cooled by another fan or blower 30a (FIGS. 2C, 2D). This blower 32a is mounted on the same shaft 34 (FIGS. 2A,"2C, 2D) as is the blower 30 and on the back I2a5.

The top wall 12al (FIG. 2A, 2D) is provided with a cork mounting hole 38 for mounting therein a cork 40, which cork 40 supports a temperature sensing means 42, such as a readout thermocouple 42a (FIGS. IA, 18, 2A, 2D) and a control thermocouple 42b, and a thermometer 420. In addition the top Wall 1201 carries sample mounting means, a hanger 44 (FIGS. 2D, 4) provided with location dimples 44a (FIGS. 2A, 2D, 4) in which sample hooks 44b carrying the solid samples I4 are placed.

MAGNETIC BALANCE ASSEMBLIES 46a-46f Disposed in registry with each solid sample 14 and arranged on the periphery of a circle are a plurality of, for example, six magnetic balance assemblies 46a46f (FIGS. 2C, 2D, 4). Each magnetic balance assembly 46a46f has a frame 46a (FIG. 4) secured at 46b (FIGS. 2C, 4) to the floor 26b (FIG. 4) of the sample chamber 26. In order to mount actuating means, such as the reed switches 48a-48f (FIGS. 3, 4) on their respective magnetic balance assemblies 46a46f, a reed switch 48a, (FIG. 4) for example, is mounted in holes 46d in the sidewall 46s of the frame 46a. A balance arm 46f (FIG. 4) is pivoted by means of rods 46g (extending from the sides of balance arm 46f) on one pair of opposed serrations 46h provided in the top of sidewalls 46e. In order to maintain the rods 46g in the serrations 46h, stops, such as bolts 461' (FIG. 4), are mounted on the top of the sidewalls 462.

The left-hand end of the balance arm 46], as viewed in FIG. 4, has a paper cup mounting platform 46k provided with a plu rality of, for example, two cup-retaining pins 46L for retaining a paper cup 46m on the platform 46k. In order to actuate the reed switch 48a when a paper cup 46m containing the softened solid 14 moves from the upper solid line horizontal position (FIG. 4) to the dotted lower and inclined position (FIG. 4), a permanent magnet rod 46!: is mounted on the balance arm 46] below the cup platform 46k. The reed switch 48a is connected at each end by lines 46p (FIGS. 2C, 3, 4) extending to insulators 46q (FIG. 4) mounted on the floor 26b (FIG. 4) of the sample chamber 26. The means utilized to balance the balance arm 46] and the paper cup 46m in the horizontal solid line position (FIG. 4) comprises balance means, such as the knurled nuts 46r (FIG. 4) which are positionable on the threaded right-hand end 46s (FIG. 4) of the balance arm 46f.

OPERATION After the solid samples 14 are mounted in the first oven 12a above the magnetic balance switches 46a-46f and the paper cups 46m are positioned on each associated cup platform 46k at time t (FIG. 9), a switch gear means power switch S1 (FIGS. IA, 5, 6, 9) on the switch gear means 50 (FIGS. 1A, 5, 6) is moved by the operator at time 1, (FIG. 9) so that switch gear means 50 is connected to the first oven 12a. In addition, an oven selector switch S2 (FIGS. 1A, 5, 6) is turned to the first oven 12a also at time 1, (FIG. 9).

AC AND DC POWER Upon closure of the switch gear main power switch S1, a neon pilot light Il'(FIGS. 1A, 3, 5, 6) having a resistor R1 (FIG. 6) in parallel with the voltage supply (indicated in FIG 6 by the legend AC SUPPLY") is energized. The circuit is protected by fuses F1, F2 (FIGS. 1A, 5, 6). Line voltage is fed to a stepdown rectifier transformer T1 (FIGS. 5, 6), the secondary of which is connected to a full-wave rectifier power supply PS (FIGS. 5, 6) having diodes Dl-D4 (FIGS. 5, 6) to provide about a 6-volt DC supply. The DC power supply PS is mounted on a heat sink HS (FIG. 5) to dissipate the heat from diodes DI--D4.

PREPARATION FOR THE OPERATION OF FIRST OVEN When the oven selector switch S2 (FIGS. 1A, 5, 6) is in the No. l oven position at time t (FIG. 9), contacts C1, C2, C3, C4 (FIG. 6) of oven selector switch 52 are in the position shown in FIG. 6 and the relay coil K7 remains deenergized, thereby maintaining its relay contacts C7, C7 (FIGS. 5, 6) closed so that power from plug P1 (FIGS. IB, 5, 6) on the switch gear means 50 and connected by lead Ll (FIG. 18) to a temperature control means or controller 52 flows through the contacts C7,C7.

POWER FOR TEMPERATURE CONTROL MEANS 52 Next a controller main power switch SW1 (FIGS. IA, 7) of the controller 52 for controlling the uniform rate of temperature rise in the first oven 12a is closed to provide power to the plug P1 (FIGS. 5, 7) at time 1, (FIG. 9). This power does not cause operation of'the controller 52 until closure of oven heater switch SW6 .(FIGS. 1A, 3) and program start switch SW7 (FIGS. IA, 7) at time 1, (FIG. 9) as hereinafter explained. The temperature control means 52 is a Model 5084 temperature controller made by Barber Coleman Company, Cleveland, Ohio.

When controller main power switch SW1 (FIGS. IA, 7) is closed at time t, (FIG. 9), the controller 52 will not cause heating above a starting temperature, such as 30 C., selected by an initial temperature control device 60 (FIG. 7). However, closure of the controller main power switch SW1 (FIGS. 1A, 7) at time 1, (FIG. 9) energizes a transformer 62 (FIG. 7), which transformer 62 energizes DC power supply 64, (FIG. 7), thus powering an oven heater power source 65 (FIG. 7) of the silicon rectifier type, an amplifier 66 and a programmer 68. The power from the oven heater power source 65 is carried by lines L6, L7, L8 (FIGS. 5, 6, 7) and plug P1 (FIGS. 18, 5, 6) and lines L9, L (FIGS. 5, 6) to contacts C7, C7 (FIG. 6) of relay coil K7 and lines L11, L12 (FIGS. 3, 6) via plug P3 to the heater circuit (FIG. 3) preparatory for the closure of oven heater switch SW6 (FIGS. 1A, 3) at time 1, (FIG. 9) to energize the heater 54a (FIGS. 2C, 3) of the first oven 12 a. The initial temperature holding device 60 is part of the pro grammer 68.

Referring to FIG. 7, the controller 52 is prepared for reception of the control signal from the control thermocouple 42b of the first oven 12a upon closure of the oven heater switch SW6 at time 2 (FIG. 9). This control thermocouple 42b is provided with a cold junction compensator 69 (FIG. 7) similar to the compensator CJCI in the lower-Ieft-hand portion of FIG. 6 and is connected by lines L15, L16 (FIGS. 6, 7) to contacts C8", C8"' (FIG. 6).

TI-IERMOCOUPLES 42a, 42b

Referring to the lower left-hand portion of FIG. 6, the relay coil K8 associated with the now-energized controller 52, remains deenergized (when the contact C4 is open and the relay contacts C8, C8, C8", C8"' remain in the position shown in FIG. 6) for the purpose of connecting the readout thermocouple lead 42a (FIGS. 2A, 2D, 6) and the control thermocouple 42b (FIGS. 2A, 2D, 6) to a temperature recording means or recorder-54 (FIGS. 1A, 1B, 7) and to the controller 52 (FIGS. IA, 18, 7) respectively. As shown in FIG. 6, the second oven 12b has a similar readout thermocouple 42a and control thermocouple 42b. The recorder 54 is a special Servo-Riter II No. FS0lW6AX0l0-DE recorder provided with six event marker pens 80a-80f(FIGS. 1A, 10) having a readout temperature range of about 50 C. to l50 C. and made by Texas Instrument, Inc., Houston, Texas.

TI-IERMOCOUPLE COMPENSATION In order that the readout thermocouple 42a (FIGS. 2A, 2D, 6) of the first oven 12aand the readout thermocouple 42a of the second oven 12 are freed of ambient temperature effects, each readout thermocouple 4211,4211 is associated with a cold junction compensator C.IC1,CJC2 (FIG. 6) respectively and a potentiometer R1, R2 (FIG. 6) respectively for calibrating purposes.

POWER FOR TEMPERATURE RECORDING MEANS 54 In order to power the recorder 54, a recorder main power switch SW2 (FIGS. IA, 8) is simultaneously closed at time I, (FIG. 9) along with the closure of the controller main power switch SW1 (FIGS. IA, 7). All circuits in the recorder 54 are energized except the temperature pen drive motor 70 (FIG. 8) and the chart drive motor 72 (FIG. 8). In order to protect the clutch 70a (FIG. 8) and gears 70!) (FIG. 8) associated with the temperature pen drive motor 70 (FIG. 8) and to eliminate waste of chart paper 720 (FIGS. 1A, 10), a time delay means circuit including the time delay relays TD7 and TD8 (FIGS. 5, 6) is utilized as hereinafter explained.

.PEN AND CHART DRIVES As shown in FIG. 8, the servomotor 70 drives gears 70b, clutch 70a and a drum 70d having an endless belt 70e extending around such drum 70d and two idler rollers or drums 70f with the temperature marking pen 70c attached to the belt 702 and in contact with the chart 72a.

The chart drive motor 72 drives a gear train 72b (FIG. 8) which gear train 72b drives a chart supply roller 72c (FIGS. 8, l0) and a takeup roller 72d (FIG. 8).

Each of the six event marking pens a-80f(FIGS. 8, 10) are mounted adjacent an electromagnetic coil 79a79f so that energization of such coils 79a79f, as hereinafter explained, will cause the free or recording end of each such pen 80a-80 to record the softening event of each sample 14 on the chart 72a (FIGS. IA, 10).

RECORDER OPERATION The closure of recorder main power switch SW2 (FIGS. IA, 8) at time 1, (FIG. 9) causes energization ofa power supply 74 (FIG. 8) which power source 74 powers a reference voltage supply 76 (FIG. 8) of the Zener type and an amplifier 78 (FIG. 8). The amplifier 78 receives the recording temperature signal from the recorder thermocouple 42a (FIGS. 18, 2A, 2D, 6) of the first oven 12a. This recorder thermocouple 42a is provided with a cold junction compensator 69 (FIG. 8) similar to compensator C.IC (FIG. 6), and is connected by lines L13, L14 (FIGS. 6, 8) to contacts C8, C8 (FIG. 6) respectively of relay K8.

The reference signal from the reference voltage supply 76 is utilized for comparison in the amplifier 78 with the recording temperature signal from the recorder thermocouple 42a of the first oven 12a to direct the movement of the servomotor 70, thereby determining the position of the temperature recording pen 70c (FIGS. 8, 10), which pen 700 is in contact with the now moving chart 72a (FIGS. 1A, 10) driven by the now-energized chart drive motor 72.

In addition, the oven power switch SW3 (FIGS. IA, 3) on the first oven 12a is also closed at time t, (FIG. 9), thereby energizing the oven blower motor 32 (FIGS. 2A, 2C, 2D), the fans 30, 30a, an internal light '19 (FIGS. 2B, 2D, 3) for the sample chamber 26 and a pilot light 17 (FIGS. 1A, 3).

The oven heater switch SW6 (FIGS. 1A, 3) is then closed at time (FIG. 9) preparatory for the initiation of the heating cycle and preparatory for the reception of the control temperature signal from the control thermocouple 42b (FIGS. 1B, 2A, 2D) of the first oven 12a by the initial temperature holding device 60 (FIG. 7) to hold the temperature in the first oven 12a below the predetermined starting temperature, such as 30 C.

OVEN HEATERS Each oven 12a, 12b has an electrical resistance-type heater 54a (FIGS. 2C, 2D, 3) mounted on the front of the back 1205 of the oven 12a, 2b by brackets 54b (FIGS. 2C, 2D) and disposed about the circulating fan 30 (FIGS. 2C, 2D) and controlled by the variable transformer 56 (FIG. 3). Energization of the heater 54a by closure of the oven heater switch SW6 (FIGS. 1A, 3) at time 1 (FIG. 9) is indicated by the pilot light I8 (FIGS. IA, 3). The first oven 12a will not operate unless the temperature in the first oven 12a is below some temperature, such as 30 C., as controlled by the initial temperature holding device 60 (FIG. 8) of the controller 52 and as indicated in the pilot light I8 due to the continued closure of the normally closed contact (K2 I (FIG. 7) of the relay CK2 (FIG. 7).

PROGRAM START time delay relay TD8. After time 1, (FIG. 9) also about 2% minutes, normally open contact CTD8 (FIG. 6) closes, thereby powering the recorder 54 through lines L4, L5 (FIGS. 5,6 and 8) and plug P6 (FIGS. 1B and 5). Thereafter the temperature pen drive servomotor 70 and chart drive motor 72 are energized.

Simultaneously, closure of the contact CKl2 (FIG. 7) causes energization of a second relay means, the relay CK-2 (FIG. 7),with resultant opening of normally closed contact CK2-I (FIG. 7) of the initial temperature holding device 60 (FIG. 8) and attendant deenergization of the initial temperature holding device 60.

Thereafter, the programmer 68 (FIG. 7) of the controller 52 controls the rate of temperature rise in the samples 14 at about 5 C. per minute as such programmer 68 receives the oven temperature signal from the control thermocouple 42!; (FIGS. 18, 2A, 2D, 6) ofthe first oven 12a.

SOFTENING EVENT MARK Referring to FIGS. 3, 4, 6, and assuming that the sample 14 above magnetic balance assembly 46a has dropped into the cup 46m (FIG. 4) so that the reed switch 48a (FIGS. 3, 4, 5) is now closed, pilot light II (FIGS. IA, 3, 5) and a second time delay means including the time delay relay TDI (FIGS. 5, 6) are energized via line L17 (FIGS. 3, 6), relay coil KI (FIGS. 5, 6) and line L18 (FIG. 6) to one side of the DC power supply PS and line L19 (FIGS. 3, 6), contact C2 (FIG. 6) of oven selector switch 52 (FIGS. 5, 6) to the other side of DC power supply PS. Energization of relay Kl (FIG. 6) causes closure of its normally open contact CKl (FIG. 6) with attendant energization of time delay relay TDI (FIG. 6) and energization of the light 11 (FIGS. 1A, 3, 5) via line L21 (FIGS. 3, 6) from relay TDl to the light II and line L22 (FIG. 6) from the lefthand side of contact CKl (FIG. 6) to one side of the AC voltage supply and via line L23 (FIGS. 3, 6) from light II through contact Cl (FIG. 6) of oven selector switch S2 and line L24 (FIG. 6) to the other side of the AC supply.

Simultaneously the closure of relay contact CKI' (FIG. 6) causes DC voltage to flow from DC power supply PS through line L25 (FIG. 6), normally closed contact CTDI (FIG. 6) of relay TDI, line L24, (FIGS. 5, 6, 8) to electromagnetic coil 790 (FIG. 8) of event marking pen 80a (FIG. 8) in contact with the chart 72a'(FIG. l0) and return lines L26, L18 (FIG. 6) to the other side of power supply PS, (FIGS. 3, 6), thereby causing deflection or movement of such event marking pen 800. After time 2 (FIG. 9), about 2 seconds after closure of contacts CKl, CKI' (FIG. 6), the time delay relay TD] (FIG. 6) causes its normally closed contact CTDI to open, thereby deenergizing the event marking pen 80a (FIGS. 8, l0) and causing it to return to its starting position.

COOL-DOWN After the operator has noted that all samples 14 have dropped into their respective cups 46m, he opens the normally closed cool-down switch SW8 (FIGS. IA, 8) at time 1 (FIG. 9), thereby deenergizing relay CKI (FIG. 6) with resultant opening ofnormally open contacts CKl-l and CK1-2 (FIG. 7) and attendantdeenergizing of relays TD7, TD8 (FIG. 6), the servomotor 70 and chart drive motor 72 (FIG. 8). Opening of normally open contact CKI-Z (FIG. 7) of relay CKl deenergizes relay CK2 (FIG. 7), thereby closing normally closed contact CK2-l (FIG. 7) and reenergizing the initial temperature holding device 60 (FIG. 7).

If the operator forgets to close cool-down switch SW8 at time 1 (FIG. 9), a final temperature holding device 60a (FIG. 7) of the programmer 68 of the controller 52 holds the temperature in the first oven 120 at a maximum temperature, such as I30 C., until such time as the operator remembers to close cool-down switch SW8.

Simultaneously with opening of cool-down switch SW8 (FIGS. IA, 7), the operator opens the oven heater switch SW6 (FIGS. IA, 3) and the door 22 (FIGS. IA, 2A, 2B, 2C, 2D) on the first oven 12a. If the operator forgets to open oven heater switch SW6, the now-reenergized initial temperature holding device 60 (FIG. 7) will reduce the temperature of the first oven 12a to the initial temperature set point of about 30 C.

During cool-down of the first oven I2a the oven main power switch SW3 (FIGS. 1A, 3) remains closed so that the blowers 30, 30a (FIGS. 2C, 2D) accelerate the cool-down of the first oven 12a. Simultaneously, the operator draws horizontal lines 8Ia-8l (FIG. 10) from the leading edge of the event marks 82a82 (FIG. 10) on the chart 720 until each line intersects the temperature line 86, such intersection giving the melting temperature of the individual samples I4.

TRANSFER TO SECOND HEATING MEANS 12b Thereafter, the oven selector switch S2 (FIGS. IA, 5, 6) is turned to the second oven 12b, thereby shifting contacts C1, C2, C3, C4 of oven selector switch S2 (FIG. 6) from the position shown in FIG. 6 to: (I) energize relay coil K7 (FIG. 6), thereby moving contacts C7, C7 (FIG. 6) to shift the heater power to oven 12b; and (2) energize relay coil K8 (FIG. 6) thus moving contacts C8, C8 (FIG. 6), C8", C8 to connect the readout thermocouple 42a (FIG. 6) of the second oven 12b to the compensator 69 (FIG. 8) of the recorder 54 and to the compensator 69' (FIG. 7) of the controller 52 respectively; and (3) to connect the pilot lights III6 (FIGS. IA, 3) and the reed switches 48a-48f of the second oven 12b preparatory for the test of the second group of solid samples 14 in the second oven I2b.

CONNECTIONS The plug PI (FIGS. IB, 5, 6) connects the heater power from the controller 52 to the switch gear means 50. The plug P3 (FIGS. IB, 5, 6) connects the switch gear means 50 to the first oven 12a to provide heater power for the heater 54a (FIGS. 2C, 2D, 3), to provide power for the oven lights "-16 (FIGS. IA, 3) and to interconnect the reed switches 48a48f (FIGS. 3, 4) to the switch gear means 50. The plug P2 (FIGS. IB, 5) performs a function similar to that of plug P3 for the second oven 12b. The plug P4 (FIGS. IB, 5, 6) connects the switch gear means 50 to the recorder 54 and provides power to operate the event marking pens a80f (FIG. 10). The plug P5 (FIGS. 18, 5, 6) connects the controller 52 to the switch gear means 50 and provides power to operate the time delay relay TD7 (FIG. 6) of the time delay circuit. The plug P6 (FIGS. IB, 5) connects time delay relay TD8 (FIG. 6) of the controller 52 to the recorder 54 and provides power for the chart drive motor 72 (FIG. 8) and servomotor 70.

The operating switches of the apparatus I0 are summarized in the following table:

TABLE I Switch Name Location SI Switch gear main power swich Switch gear means 50. Oven selector switch Switch gear means 50. Controller main power switch Controller 52. SW2 Recorder main power switch Recorder 54. SW3 Oven main power switch for blowers Ovens 12a, 1211.

30, 30a, motor 32 and light It). SW6 Oven heater switch for heaters 5411.. Ovens 12a, 12b. SW7 Program start switch Controller 62. SW8 Cool-down switch Controller 52.

SUMMARYOF THE ACHIEVEMENT or THE OBJECTS or THE INVENTION It will be recognized by those skilled in the art that the objects of this invention have been achieved by providing apparatus 10(FlGS. IA, 18, ZA-ZD, 3-6) for determining the softening temperature of solid samples 14, which apparatus 10 maintains the rate of temperature rise in the heating means 54a at 5 C.i0.02 C. per minute automatically, thereby resulting in improved precision and accuracy in the determination of the softening point; permits the testing of a plural number of specimens 14, such as 6, thereby permitting plural numbers of, such as three different, specification samples 14 to be measured at one time with attendant reduction of test total time by about one-third; records permanently and automatically the softening point of each pitch specimen 14, thereby freeing the operator from the tedious task of recording during the heating phase of the softening point determination; and results in an accurate determination of the softening point characteristics of electrode binder pitches to prevent errors or deviations from the customer specification and the unnecessary scrapping of suitable electrode binder pitches.

While in accordance with the patent statutes preferred and alternative embodiments of this invention have been illustrated and described in detail, it is to be particularly understood that the invention is not limited thereto or thereby.

We claim:

1. Apparatus for determining the softening point of a solid sample and having:

a. first heating means and a second heating means, each for containing a solid sample and for heating said solid sampie to its softening point at a predetermined uniform rate of temperature rise and having sensing means for continuously measuring the temperature within said first heating means and said second heating means during the heating of said solid sample,

b. switch gear means connected to said first heating means and said second heating means to alternately connect the first heating means and then the second heating means to said apparatus,

c. temperature control means connected to said switch gear means for controlling the uniform rate of temperature rise in the connected one of said first heating means and in said second heating means, temperature recording means connected to said temperature control means and said switch gear means for recording the temperature rise in said solid sample and the softening point of said solid sample, c. said temperature control means having event marking means connected to said switch gear means, and each of said first heating means and said first heating means having:

l. sample mounting means for mounting said sample therein;

2. a magnetic balance assembly in registry with said mounted sample and adapted to receive said sample when said sample reaches its softening point and falls into said magnetic balance assembly, thereby causing movement of said magnetic balance assembly, and

. actuating means adjacent said magnetic balance assembly, connected to said switch gear means, and operable by said movement to cause said switch gear means to move said event marking means to record said softening point.

2. The apparatus recited in claim 1 wherein said sensing means has a recording sensing means connected to said temperature recording means for supplying a recording temperature signal to said temperature recording means.

3. The apparatus recited in claim 1 wherein said sensing means has a control sensing means connected to said temperature control means for supplying a control temperature signal to said temperature control means.

4. The apparatus recited in claim 2 wherein said temperature recording means has a temperature recording pen and drive means for said temperature recording pen, said drive means being operable by said recording temperature signal to move said temperature recording pen.

5. The apparatus recited-in claim' 4 wherein said temperature recording means has a reference supply means for providing a comparison basis for said recording temperature signal.

6. The apparatus recited in claim 3 wherein said first heating means and second heating means have an o ve n ower source and said temperature control means has an mitia temperature holding means connected to said oven power source for receiving said control temperature signal and for controlling said oven power source so that temperature in the connected one of said first heating means and said second heating means remains below a predetermined starting temperature.

7. The apparatus recited in claim 1 wherein said switch gear means has a second time delay means connected to said actuating means, and said event marking means is connected to said second time delay means, said second time delay means being actuated by said movement and operable to move said event marking means.

8. The apparatus recited in claim 3 wherein said first heating means and said second heating means have an oven power source and said temperature control means has a final temperature holding means connected to said oven power source for receiving said control temperature signal and for controlling said oven power source so that the temperature in the connected one of said first heating means and said second.

heating means remains below a predetermined starting temperature.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,587,293 D d June 28, 1971 Glenn E. Bowers et a1. Inventofls) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 23, "do" should read so line 51, "2B" should read 2D Column 4 line 71,"('FIGS 5 ,6)" should read (FIG. 6) Column 5 line 49, 7" should read 8 Column 6, line 21, "SOs-80" should read 80a-80f Column 8, line 20, "8la-81" should read 8la-8lf line 21 "82a-82" should read 82a-82f line 36, after "12b" insert and control thermocouple 42b (Figure 6) of the second oven 12b Signed and sealed this 30th day of May 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM po'wso $69) USCOMM-DC suave-pea .5, GOVERNMENT PR'NTING OFF'cEI I". O-lii-ll 

